Proportionalizing control



y 2, 1944' E. M. SORENSEN 2,347,714

PROPOR'I. IONALI ZING CONTROL Filed Sept. 5, 1941 4 Sheets-Sheet 1 IIEUZfonwea M SOQEAV'SE/V roe/ 57! y 1944- E. M. SORENSEN 2,347,714 I'PROPORT IONALIZ ING CONTROL Filed Sept. 5, 1941 4 Sheets-Sheet 2 I 35 FE 3 3b EaMIPQ/X Sonia/v55 Ir NE/S y 2, 1944- E. M. SORENSEN 2,347,714

PROPORTIONALI Z ING CONTROL Filed Sept. 5, 1941 4 Sheets-Sheet 350144490 M GORE/v65 rroQuE/f y 1944- E. MSORENSEN 2,347,714

PROPORTIONAL I Z ING CONTROL Filed SeptL 5, 1941 4 Sheets-Sheet 4 I; 'E'7 v e0 a g an 4kp M JOIQENSE/V Patented May 2, 1944 UNITED STATES PATENTOFFICE PROPORTIONALIZIN G CONTROL Edward M. Sorensen, Coscob, Conn.Application September 5, 1941, Serial No. 409,702

29 Claims. (Cl. 175-320) (Granted under the act of March 3, 1883, as

amended April 30, 19

The invention described herein may be manufactured and used by or forGovernment for governmental purposes, without the payment to me of anyroyalty thereon.

This, invention relates to a power control systen; herein designated asa proportionalizing con- -The primary object of the invention is toprovide an improved control system which in itself has negligibleinertia, and which has characteristics tending to-overcome objectionableefiects of inertia in bodies controlled by the system, or, in otherwords, to prevent so-called over-shooting and hunting. This isaccomplished by making the amount of the contro1 effect, or correction,proportional to the magnitude of adjustment that is required. In thismanner the system may be said to anticipate the necessary control effectat any moment, so that when a large adjustment is required acorrespondingly large control effect will be exerted, and when a slightadjustment is required the control effect will be correspondinglyslight.

The principle of the invention follows the analogy of moving a massexactly into a'given position in the shortest possible time. A largeforce is first applied toovercome inertia and start the mass moving,after which the moving force is constantly reduced as the massapproaches the given position, until finally the moving force is reducedto zero and the mass comes to rest exactly in the given position withoutoverriding or hunting. Whether the inertia of the mass is large or smallwill be immaterial if the moving force is always strictly proportionedto the remaining adjustment that is required, for as soon as the massmoves toward the given position, the applied energy,

whether large or small in amount; will be reduced in accordance with theresponse produced thereby. It may be assumed in practical applicationsthat a retarding force of some kind, such as friction, is present totend to arrest the motion of the mass when the moving force isdiscontinued, but aretarding'force is not necessary to practice theinvention.

In the presentinvention the control energy is normally limited to avalue which is insu-fllcient to produce a control efiect continuously.Means are provided for storing this energy until a sumcient amount hasaccumulated to exert a control effect. The stored, energy is thenreleased by a trigger means, and a momentary control, or corrective,effect is produced. Thus, the control -eiiect,- when required. willnormally be exerted periodically, the time interval between successivetrigger means. It will be seen, then, thatif the,

' amount of control energy is small the control effects will occur lessfrequently than ii. the

amount of control energy is large. A further characteristic of thepresent invention is that when the control energy exceeds apredetermined amount, corresponding to the requirement for a large orabnormal correction, a continuous control effect may be exerted. Inother words, as the control energyis increased, the length of timerequired to store sufllcient energy to actuate the trigger means becomesless, until finally the' amount of'energy is sufllcient to exert acontinuous control eflect. a

In the following specification and drawings the control energy isin theform of electrical energy, the energy storing means comprises acondenser, and the energy releasing, or trigger, means comprises agaseous discharge tube, but it is to be, understood that the presentembodiments are for purposes .of illustration only and are in no wayintended to limit the invention. It is distinctly within the scope ofthe invention to employ other forms of energy storing means and energyreleasing means, and to use other forms of energy, the

only limitations being those imposed by the scope of the appendedclaims. Additional objects and advantages will be apparent as thedescription proceeds in connection with the accompanying drawings.

This case i a continuation December 23, tionalizing circuits, as hereindisclosed. In the above-mentioned applications the proportionaliz ingcircuits are employed in control systems designed to regulate or controla particular operation, the performance of which would normally exhibitinertia effects rendering unsatisfactory known conventional controlsystems. It is recog-. nized, however that the various embodiments ofproportionalizing circuits herein illustrated are capable of generalapplication to any system employing control energy to regulate powermeans, and it is therefore not intended to limit the present inventionto use with any particular system or systems, such, for instance, as areshown in the parent'applications above referred to.

In the drawings:

Figure 1 illustrates one basic embodiment ofin part or s. N. 335,517filed May 16, 1940, and S. N. 371,368 filed 1940, both of which includepropor-' interval of time.

ing two control relays and two sources of control current.

Figure 3 illustrates a modification of the system shown in Figure 2 bythe addition of reactance elements to increase the time intervals forcharging and discharging of the condensers.

Figure 4 is a modification of the system shown in Figure 2, adding areactance to increase the time intervals, but having fewer elements thanthe system of Figure 3 through the use of reactance and resistanceelements in common to both sides of the push-pull arrangement, and alsoincluding rebalancing means.

Figure 5 illustrates a system corresponding to the system shown inFigure 1 except that the condenser and gaseous discharge tube have beenrearranged in the circuit, and a reactance has been added to increasethe time intervals of operation.

Figure 6 illustrates the system of Figure 5 modified to provide apush-pull arrangement, and having a resistance and reactance common toboth sides of the push-pull system.

Figure 7 illustrates a modification basically similar to the systemshown in Figure l, but substituting a variableresistance for the vacuumtube in the source of control current.

Figure 8 illustrates a modification oi the system shown in Figure '7.

The circuit of Figure 1 is seen to consist oi a condenser 26 and a neontube 21 connected in series and parallel with the relay 28, condenserthe plate current in plate 1 will steadily increase so that the rate atwhich the neon tube 21 and condenser 26 operate to actuate relay 26 willincrease. When the plate current is 0! sumcient value to maintain therelay continuously closed. the proportionalizing circuit has no moreeffect until the grid potential is made more'negative to a valueslightly less than the potential at which the relay is continuouslyclosed. Then the proportionalizing circuit will again actuate the relayintermittently at a decreasing rate until the grldpotential reaches itsnormal value which is a blocking potential sufliciently nega tive tointerrupt the flow of plate current.

In this manner, energy may be supplied to a motor or other power meansin the circuit 29 in a pulsating manner,.with the rate of pulsationsbeing in direct proportion to the distance the controlled device is fromthe point corresponding to the above-described normal value of gridpotential. However, it a reduction gear of a sizeable ratio is employed,the motion of the con- I trolled element will appear to be substantially26 and relay 26 being commonly connected to the plate lead 24 fromvacuum tube 3. At the junction of the neon tube 21 and condenser 26 is aresistor IS, the other terminal of which is connected as at I to theplate supply potential. To the Junction of the neon tube 21 and therelay winding is connected a resistor I! having its other terminal alsoconnected to side I of the source of potential. Grid 2 of vacuum tube 3has normally impressed thereon a negative potential. The opposite sideof the grid potential as at 4 runs to cathode 5, also connected to thenegative side 6 of the plate potential.

To illustrate the actio of the above circuit, assume that there is anincrease in plate current in the plate I in the order of 30microamperes, due to a less negative potential on grid 2, in response toa received signal. This causes condenser 26 to take a charge throughresistor i9, and at the same time a potential is set up across resistorl1. As. the charge builds up on condenser 26, the potential acrossresistor 18 falls until the difference in potentials across resistors l1and I9 is of a suliicient value to cause ignition of neon tube 21. Whenneon tube 21' ignites, a discharge path through relay 28 and neon tube21 is provided for condenser 26. The current flow through relay 28caused by the discharge of condenser 26 is in excess of the currentrequired to close the relay, so that the same will close during thedischarge of the condenser. Thus, the motor or other power device incircuit with the line 29 is put in operation for a brie! When condenser26 is discharged, the neon tube extinguishes, since resistor I9 isprovided with a great enough resistance to prevent the passing ofcurrent oi sufflcient value to maintain the neon tube ignited. Condenser26 being discharged, and neon tube 21 being extinguished, the circuitimmediately starts to recharge condenser 26 through resistance l9,whereupon the cycle is repeated. If the potential on grid 2 becomesstill less negative,

continuous and progressive in its rate 01' increase or decrease.

The values of condenser 26 and resistance l6 determine the rapidity withwhich the proportionalizing circuit will operate for a given platecurrent. The value of resistor il determines the plate current requiredto initiate both the proportionalizing action and continuous operationof the relay.

It will be seen that the proportionalizing circuit operates as afunction oi current, wherein as the plate current is increased acrossthe proportionalizihg circuit to an amount corresponding to theionization potential of the neon tube,

the circuit will start to function, due to the increased voltage dropacross resistor As the current continues to increase beyond the limitsof the proportionalizing circuit, the proportionalizing control willstop and the power means or other device will move at its full rate, butas soon as the mechanical elements of the control approach the desiredsetting, the proportionalizing circuit functions at a rate equal to theamount the control is out of balance, corresponding to the departurefrom the normal value of grid potential. Thus, as the control is broughtinto balance, the proportional rate becomes slower until the balance isjust reached, and difflculties from hunting or over-shooting areavoided.

It will be understood that by adjusting the values of resistor IT or thespring tension on the relay armature, the proportionalizing circuitcould be designed to control the operation or the relay 28 also duringthe maximum operating plate current so that a proportionalizing controlmight be maintained throughout the range of operation of the controlleddevice.

The system illustrated in Figure 2 constitutes a push-pull adaptation ofthe system shown in Figure 1 for operating two control relays to producepositive response to control eflects in two senses or directions. Twocontrol voltages 2| and 22 are fed into a twin triode tube 23 andindividually control respective plate circuits 24 and 26. The action ofeach plate circuit corresponds to the action described in connectionwith Thus the plate current in the circuit 24 varies in accordance withthe control voltage in the grid circuit 2| to vary the charging time ofcondenser 26. As in the previously described embodiment the condenser 26accumulates a charge in each cycle or operation sufficlent to ignite thegaseous discharge tube 21 and produce a momentary energization of relay28 to complete a control circuit 28.

The other half of the system, comprising resistances l8 and 28,condenser 38, gaseous, discharge tube 3i, relay 32 and control circuit83, correspond to the elements 11, I3 and 28 to 28, and function in acorresponding manner under the control of the voltage in the gridcircuit 22. Plate potential for the twin circuits is applied at theterminals I, 8'.

The general object of the push-pull arrangement in Figure 2 is toproduce a control eflect in one direction or sense by means of thecontrol circuit 28, and to produce a control effect opposite indirection or sense through the control circult 33. Hence in the normaloperation of this systemv the relays 28. and 32 do not operate at thesame time. This condition is ordinarily assured by'the fact that thecondition producing a control effect in the grid circuit 2I wouldpreclude the producing 01 a control effect in the grid circuit 22, andvice versa. 1 Since obviously it should never be necessary to producesimultaneous corrections in opposite directions or senses in theembodiment shown in Figure 2, the ener'gization oi. circuits 28 and 33at the same time may be positively prevented by making it necessary forone relay to be inactive in order for the other to operate, this beingdone by connecting the supply line 38 to the back contact of the tworelay armatures. In this manner at least "one of the armatures must bein its back position to establish a circuit to the supply line 38. lays28 and 32 should operate in unison no control effects would then beexerted by either one of the relays.

It is possible, however, to use the push-pull adaptation of Figure 2 insituations requiring the operation of both relays 28 and 32 at the sametime, and it is not intended to limit the invention so as to excludesuch operation, since by connecting line 38 to line instead or line 36energization of the control circuits 28 and 33 independently of eachother could be established. To obtain simultaneous operatipn oi. therelays 28 and 32, howevenwould require that the signal responsive partof the system (not shown) be adapted to impress 'sufllcient controlvoltages upon the grids 2| and 22 at the same time to cause controlcurrents to flow in both plate circuits 28 and 28,

Figure 3 illustrates a variation of the proportionalizing circuit in.which reactances such as condensers 8i and 82 are connectedin parallelwith the resistances I8 and 28 respectively. This arrangement hastheeflect of increasing the intervals of time required for thecondensers 26 and 38 to receive their charges and similarly the timesrequired to discharge. It will also be noted in Figure 3 that theleads88 and 36' are not connectedto the leads 38 and 36, in order tomake possible the simultaneous energization of the conductors 28 and 33by the relays 28 and 32 in response to the control eflects imposedthereon. In all other respects the system inFigure 3 operates in thesame manner as the system shown in Figure 2, and the elements of Figure3 which are common to Figure 2 have been given corresponding referencenumerals.

It a strictly push-pull operation is desired, that is, if the relays 28and 82 are never required to p r simultaneously. the number or elementsin the system may be reduced as shown in Fig- Iif both 'reure 4. Underthese conditions, when onlybne oi the relay; is operating at one time,the system of Figure 4 will function in the same manner as that ofFigure 3 since the resistance 88 can take the place'oi either theresistance I8 or the resistance 28, and the condenser II can take theplace of either the condenser 8| or the condenser 82, depending uponwhether the relay 28 or the relay 32 is in operation. (The leads 3! and38 may be interconnected with 35' and 36', after the manner of Figure 2,if desired.)

Figure 4 also includes balancing means corresponding to that shown inFigure 4 or S. N. 335,- 517. Elements of the balancing means common tothe parent application have been given the same reference numerals andcomprise leads I21, I28, dual potentiometer I38, resistors I3I and I32,batteries I39, I80, and potentiometer-arms I8I, I82. The cathode lead 8"is grounded to the negative side of the plate supply and connectedbetween the resistors I3I and I32 since the present Figure 4 does notinclude compensation for emission variation due to changes in filamentpotential as shown in the parent application. Points I21 and I28 then,represent the signal input to the present proportionalizing andbalancing combination and correspond to the respective terminals I21 andI28 in the output circuit of the rectifier and amplifier units in theparent application, but it is understood that the application of thepresent invention is not limited to the particular receiver andamplifier embodiments disclosed in the parent cases, nor is it limitedto the particular types of systems disclosed therein. Batteries I39 andI are of the same potential but are connected to the potentiometer armsI and I82 in opposite polarity arrangement so as to buck the potentialexisting across the potentiometer arms and provide a desired potentialacross grid leads 2| and 22 when the potential existing across thepotentiometer arms is at the desired relation to the potential of thebatteries. A dual potentiometer of this type is of advantage incombination with the rectifier circuit of the parent application S. N.335,517 since it provides Y an equal load on both sides of the rectifiercircuit between arm I8I to ground and arm I82 to ground. Another reasonfor using dual poten- .tiometers in this circuit is-the diilicultyoirobtaining potentiometers of the wire wound variety having asufliciently high resistance. in a single unit. Thus the dualpotentiometers provide twice the resistance of a single unit and supplya satisfactory load impedance for use in the output of a rectifier unit.The twin-triode tube 8, by reason 0! having its grids connected to theresultant potentials present'in the leads 2I and 22, functions inresponse to an unbalance of the potentiometer circuit to control therelay circuits 28 and 33 to the motor in the same manner heretoforedescribed.

In Figure 4 the numeral 9 represents 'the motor or power means to beoperated according to the effects of the incoming signal as received atI 21; I28, the two windings I8 and II providing for opposite directionsof rotation of the motor under' the control of the relay circuits 28 and33.

The motor 8 may operate through reduction gearing or other means todrive variousigmechanismsin the manner described in the parentapplications, either the motor or itsi-reduction gearing being alsomechanically connected-"to the potentiometer arms I and I82, in such amanner as to rebalance the circuit in response to operation of themotoii.

-dividual resistances The motor 9 may include a magnetic brake andclutch, limit switches, and a centering mechanism, as illustrated in S.N. 335,517. Also, the i-ebalancing of the system,may be accomplished .byother circuit arrangements such, for instance,

as are illustrated in other embodiments in S. N. 335,517, the presentrebalancing arrangement being merely illustrative of a preferred arrangement for use with a particular receiver and amplifier.

The system in Figure is similar to one-half oi the push-pull systemshown in Figure 3 except that the condenser 28 and gaseous dischargetube 21 have been interchanged so that the latter is now conne'cted tothe plate lead 24 and the relay 28. The condenser 28 has one terminalconnected at the Junction between the relay 28 and the resistance l1 andhas its other terminal connected at the Junction between the gaseousdischarge tube 21 and the resistance l9. A currentof sufiicient value inplate circuit 24 will charge the condenser 28 through the resistance "toa potential which will cause ignition of the gaseous discharge tube 21.Thereupon the condenser 26 will discharge causing the operation of therelay 28. Thereafter the condenser 26 will receive a new charge andrepeat the cyclic operation-Just described as in the other species, theresistance ll being normally suilicient to prevent continuousenergization of the relay 28 by the control current in the plate circuit24. At the beginning of each cycle of operation the initial fiow ofcharging current for condenser 2! reduces the potential across thegaseous discharge tube 2! so that it can not ignite until the charge onthe condenser 25 has developed a potential equal to the ignitionpotential of the gaseous discharge tube. The action of the system inFigure 5 difi'ers from that of the systems in Figures 1 to 3 in thatproportionalizlng is extended over a considerably greater range byreason of the fact that the control current flowing in the plate circuit24 must rise to a far greater value to maintain the relay closed than inthe systems of Figures 1 to 3. In Figure 5 a battery 58 andpotentiometer 56 having a slider on the control grid connection 2i isillustrated as a specific means for regulating or adjusting the controlvoltage affecting the plate circuit 24. It is understood, however, thatany other source of control voltage responsive to the condition to becontrolled may be applied to the grid connection 2| to govern the platecircuit 24.

' Figure 6 illustrates a system embodying the teachings brought out inthe system illustrated in Figures 4 and 5. The condenser and gaseousdischarge tube are arranged as in Figure and the adaptation to apush-pull rrangement is made as in Figure 4. The operation of each relayis the same as the operation described in connection with the system ofFigure 5, and the same advantages are obtained.

Figure 5 may also be modified according to Figure 3, instead. of Figure4, by providing in- II and 20, and individual reactances 4| and 42, forthe two sides of the circuit, for simultaneous operation of the relays2. and 32.

1 Figures 7 and 8 illustrate modifications of the Droportionallzingcircuits without a vacuum tube amplifier connected in the circuit.Heretoi'ore it has been considered necessary to employ a vacuum tubeamplifier to operate electromagnetic relays from control circuitscarrying feeble control currents, but in theembodiments now to bedescribed the proportionalizing system operates equally well without theuse oi vacuum 'tubes. It may be pointed out that the function of thevacuum tube in the proportionallzing circuits of the present inventionis merely to serve a variable resistor whose resistance is beingcontrolled by the variation of the grid potential on the grid oi thetube. In Figures 7 and 8 the proportionalizing circuit operates a relayby changes in the conducting path of a photoelectric cell, or othervariable resistance, taking the place of the vacuum tube shownin thepreviously described embodiments. Thus, the variable resistance 88 inFigure 7 may be described as representing a light sensitive cell orother variable resistance changing its value in response to thecondition to be controlled. The same is true of Figure 8, showing acircuit modification which has the efi'ect of changing theproportionallzing time for a given change in control current; Figure 8however is not'a basically difierent system, but is merely a slightmodification to produce a diflerent characteristic operation. Thenumeral 8| represents an electrical supply source, and 62 in Figure 7indicates an additional resistor which is found to improve the operationof the system.

The systems shown in Figures 7 and 8 iunctlonsimilarly to the systemspreviously described in that the energy supplied to the line II isnormally insuificient to operate the relay 28. This energy, under thecontrol of the variable resistance u 68, builds up a charge on thecondenser 26 until the breakdown potential of the gaseous discharge tube21 is attained, the condenser 28 then discharging through tube 21 tomomentarily energize the relay 28 and close the power circuit 28. Thisoperation accomplished, the condenser 26, which is now discharged, againbegins to charge for: a cyclic repetition of the operation, the timeintervals oi the cyclic operations being governed by the values of thevariable resistance 88, Just as it was governed in the a previousembodiments by the variable efiectlve resistance of a three-elementvacuum tube.

The proportionalizing systems herein disclosed require a relatively fewnumber of elements to provide the advantages set out. The principalelement, in addition to the relay, resistors and condensers, is a tubeor envelope having inside a gas whose characteristics are such that thegap between a pair of electrodes will break down or ionize with adefinite potential impressed across the terminals. A condenser isselected having a value in conjunction with a resistor which will set upa time constant for the desired frequency of operation of theproportionalizer system under given conditions. In the modificationsillustrated, the condenser charges to a given value equal to theionization potential of the gas filled tube, and then discharges throughsaid tube and relay to produce the desired control efiects. The relayactuations by the proportionallzer may be used to control an electricmotor or any electromechanical servomotor device. A relay oi. the typeillustrated not necessary to the invention, however, as any'other typeor power controlling device may be sub atituted. In some situations amere resistor may be substituted for the relay if it is only desired tosecure a pulsating voltage at a controlled rate dependent upon avariable input voltage, or ren which is varying in accordance with the:lesponse to some controlling element, or condion. I

In the use of a magnetic relay the present proportionalizing' systemsprovide an improved manner oi operating the relay within very closelimits of the put-in and drop-out current. In this manner they enablethe using of an insensitive relay to sensitively control a large amountof power from an exceedingly small fraction of the controlled power.

It will, therefore, be seen from the above description, that thisinvention can be used wherever it is desired to efiect a change in thespeed of motion, or to stop a moving body, and will accomplish thischange or stop with the most efficient consumption of power and in theshortest possible time, while maintaining extreme accuracy of positionsetting. Likewise the proportionalizing circuit could be reversed toprovide a means for proportionalizing the application of power instarting a device in motion in order to bring the device from. rest upto maximum speed in the ,smoothest possible manner by controlling theincrements of power in a progressive fashion. Specific applications orthe proportionalizer might be for use in slowing down a train at arailroad terminus, for use as a control for rolling mill machinery, as atemperature control for use with ovens where the temperature must beincreased ,gradually and in small increments, or control for annealingovens.

The above uses are merely illustrative oi? the 0 almost unlimited fieldsof application of this control. Additional advantages and fieldsofapplication will occur to those skilled'in the art, and it isaccordingly intended that the invention be limited only by the scope orthe appended claims. I

I claim:

1. The method of exerting a resultant control eflect proportional to thevalue of a source of control energy comprising cyclically accumulatingand releasing said energy to exert said control effect, and causing thefrequency of said cyclical operation to vary in accordance with thevalue of said energy.

2. The method of controlling the energization of power means inaccordance with a source oi. varying control energy comprising storingsaid energy when the amount of said energy is less I than that requiredto energize said power means,

and discharg n said stored energy to energize said power means when theamount of said stored energy b'ecomes equal to said required amount.

3. The method of controlling the energization of power means inaccordance with a source of varying control energy comprising storingsaid energy when said energy is less than the amount required toenergize said power means, discharging said stored energy at intervalsto periodically energize said. power means when the amount of saidstored energy becomes equal to said required amount, and continuouslyenergizing said power means when said control energy equals or exceedssaid required amount.

4. In a variable electrical circuit associated with a mechanicaliollow-up system adapted to respond to the variations of said electricalcircuit, means for compensating for the inertia'in the response of themechanical system to said electrical circuit.

5. An electrical circuit for controlling the energization of power meansin accordance with a source of varying energy external to said circuitpredetermined value of energy, a source of energy iting the energydelivered from said source to an amount less than said predeterminedvalue to which said control element is responsive, means for applying tosaid variable-means the varying energy from said external source toso'control said variable means as to increase the amount of energydelivered from said source in accordance with the varying energy ofsaid-external source, and means for accumulating said energy when sameis below the predetermined value and discharging same at intervals intosaid circuit to thereby increase the value of energy in said circuit toamounts'in excess of saidpredetermined value while the amount of energybeing delivered from said source is less than said predetermined value.

6. A proportionalizing control means comprising a control elementresponsive to a predetermined value of energy. a circuit for energizingsaid control element, and means for accumulating said energy when thesame is below said predetermined value and discharging same into saidcircuit at intervals tooperate said control element, said dischargebeing withheld until the value of said accumulated energy exceeds saidpredetermined value when the amount of energy supplied is less than saidpredetermined value.

'7. A proportionalizing control means. responsive to a varying voltageto exert a resultant control effect proportional to the value of saidvoltage, comprising cyclically operating energy accumulating andreleasing means for energizing a control relay, the frequency of saidcyclical operation varying in accordance with the value of said voltage.I

8. A proportionalizing control means responsiveto a varying voltage toexert a resultant control etlfect proportional to the value of saidvoltage comprising a condenser charged by said voltage, discharge meansfor said condenser, and a relay for accomplishing said control effects,said relay being energized by the discharge of said condenser.

9. In a system for controlling the energization of power means inaccordance with a source of varying control energy, means for storingsaid comprising, a control element responsive to a 0 energy when theamount of said energy is less than that required to energize said powermeans, and means for discharging said stored energy to energize saidpower means when the amount of said stored energy becomes equal to saidrequired amount.

10. In a system for controlling the energization of power means inaccordance with a source of varying control energy, means for storingsaid energy when said energy is less than the amount required toenergize said power means, means for discharging said stored energy atintervals to periodically energize said power means when the amount ofsaid stored energy becomes equal to said required amount, and means forcontinuously. energizing said power means when said control energyequals or exceeds said required amount.

11. In a relay control system, a relay having an energizing circuit, asource of control current connected to said circuit, a resistance insaid circuit to normally limit said control current to values insumcientto operate said relay, a condenser and gaseous discharge tube connectedwith said circuit so that upon ignition of said gaseous discharge tubesaid condenser is provided with a discharge path through said energizingcircuit to operate said relay, and

means utilizing said source of control current to charge said condenser.

12. In a relay control system, a relay having an energizing circuit, asource of control current connected to said circuit, a condenser andgaseous discharge tube connected with said circuit so that upon ignitionoi said gaseous discharge tube said condenser is provided with adischarge path through said tube and said energizing circuit to energizethe latter tooperate said relay, and a resistance associated with saidcircuit to create a voltage drop efiective to enable said source oicontrol current to charge said condenser to a potential sufiicient toignite said gaseous discharge tube.

13. In a relay control system, a relay having an energizing circuit, asource of varying control current connected to said circuit, saidcontrol current being normally insufiicient to operate said relay, acondenser and gaseous discharge tube connected with said circuit so thatupon ignition of said gmous discharge tube said condenser is providedwith a discharge path through said tube and said circuit to energize thelatter to .operatesaid relay, and a resistance associated with saidcircuit to create a voltage drop in said control current efiective toperiodically charge said condenser to a potential sufiicient to ignitesaid gaseous discharge tube anddischarge said condenser into saidcircuit to energize said circuit to operate'said relay momentarily atintervals in accordance with the value of said control current when saidcontrol current is insufiicient' to continuously operate said relay.

'14. In a relay control system, a relay having an energizing circuit, asource of varying control current connected to said circuit, saidcontrol current being normally insuiilc'ient to operate said relay, acondenser and gaseous discharge tube connected with said circuit so thatupon ignition of said gaseous discharge tube said condenser is providedwith discharge path through said tube and said circuit to energize thelatter to operate said relay, and a resistance associated with saidcircuit to create a voltage drop in said control current effective toperiodically charge said condenser to a potential sufiicient to ignitesaid gaseous discharge tube and discharge said condenser into saidcircuit to energize said circuit to operate said relay momentarily atintervals in accordance with the value of said control current when saidcontrol current is insufiicient to continuously operate said relay, anda resistance associated with said circuit to normally prevent thepassing of control current of sufilcient value to maintain said gaseousdischarge tube ignited.

15. In a relay control circuit, said relay being actuable at apredetermined current value, a source of electrical energy in saidcircuit; supply controlling means for supplying to said relay current inamounts varying from below to. above said predetermined value; meansassociated with said relay circuit for actuating said relayintermittently when the current supplied from said supply means is lessthan the said predetermined value; said means comprising a resistance inseries with said relay, a circuit connected in parallel with said relayand said resistance, said last-mentioned circuit having a condenser andresistance in series arrangement, a gaseous discharge tube having oneterminal connected to mentioned resistance and having the other terminalconnected to the Junction between said the junction between said relayand said first condenser and said second mentioned resistance in saidparallel circuit, said gaseous discharge tube having an ionizationpotential less than the voltage drop across said first mentionedresistance, and said second mentioned resistance being of sufilcientvalue to limit the current flow therethrough to les than thedeionization cur-' rent oi said gaseous discharge tube.

16. A relay control circuit as defined in claim 15 wherein there isfurther provided a reactance element in parallel wtih said secondmentioned resistance to lengthen the time intervals of said intermittentactuations.

17. In a relay control system, a first circuit comprising a relay and aresistance in series arrangement, a second circuit connected in parallelwith said first circuit,said second circuit having a condenser andresistance in series arrangement, and a gaseous discharge tube havingone terminal connected to the junction between said relay and said firstmentioned resistance, and having the other terminal connected to thejunction between said condenser and said second mentioned resistance,the other ends oi said resistances being connected together and to oneline of a som'ce of control circuit, and the other side of said relayand said condenser being connected to the other line of said source orcontrol current.

18. In a relay control system, a first circuit comprising a relay and aresistance in series arrangement. a second circuit connected in parallelwith said first circuit, said second circuit having a condenser andresistance in series arrangement, a gaseous discharge tube having oneterminal connected to the'junction between said relay and said firstmentioned resistance and-having the other terminal connected to thejunction between said condenser and said second mentioned resistance,the other ends of said resistances being connected together and to oneline of a source of electrical supply, and the other side of said relayand said condenser being connected to a source oi control current, and asecond pair of parallel circuits identical with those Just described andconnected therewith in push-pull" arrangement, said second pair 01'circuits including a second relay and a second source of controlcurrent, and having a connection to said one lineof a source ofelectrical supply in common with said first mentioned pair of circuits.

19. In a relay control system, a pair of parallel circuits, the firstcircuit comprising a relay, a first resistance, a second resistance, anda second relay serially connected in the order named; the

second circuit comprising a first condenser, a first resistance, asecond resistance, and a second condenser seriaily connecte a firstgaseous discharge tube having one terminal connected to the Junctionbetween said first relay andsaid first resistance in said first circuitand having the other terminal connected to the Junction betweensaidfirst condenser and said first.

, between said second resistance and second condenser in said secondcird in the order named:

cuit; a first source of varying control current connected to said firstrelay and said first condenser; and a second source of control currentconnected to said second relay and said second condenser.

20. In a relay control system, a pair of parallel circuits, the firstcircuit comprising a relay, a first resistance, a second resistance, anda second relay serially connected in the order named; the second circuitcomprising a first condenser, a first resistance, a. second resistance,and a second condenser serially connected in the order named; afirstgaseousdischarge tube having one terminal connected to the junctionbetween said first relay and said first resistance in said first circuitand having the other terminal connected to the junction between saidfirst condenser and said first resistance in said second circuit; aconnection between said two circuits uniting the junction be-' tweensaid first and second resistances in said 'flrst circuit and thejunction between said first and second resistances in said secondcircuit, said connection leading to a source of electrical supply; asecond gaseous discharge tube having one terminal connected to thejunction between said second resistance andsaid'second relay in saidfirst circuit and having the other terminal connected to the junctionbetween said second resistance and said second condenser in said secondcircuit; a first source of varying control current connected to saidfirst relay and said first condenser; a second source of control currentconnected to said second relay and said second condenser; a firstreactance connected in parallel with said first resistance in saidsecond circuit; and a second reactance connected in parallel with saidsecond resistance in said second circuit.

21. In a relay control system, a pair of parallel circuits, the firstcircuit comprising a first relay, a first resistance, a, secondresistance and a second relay serially connected in the order named; thesecond circuit comprising a first condenser and a second condenserconnected in series; a first gaseous discharge tube having one terminalconnected to the junction between said first relay and said firstresistance and having the th r terminal connected to the junctionbetween said condensers; a second gaseous discharge tube hav-- ing oneterminal connected to the junction between said second resistance andsaid second relay and having the other terminal connected to thejunction between said condensers; a third resistance having one terminalconnected to the junction between said first and second resistances and:having the other terminal connected to the junction between saidcondensers; a reactance in parallel with said third resistance; a sourbeof electrical supply connected to the junction between said first andsecond resistances; a first source of control current connected to saidfirst relay. and said first condenser; and a. second source of controlcurrent connected to said second relay and said second condenser.

22. In a relay control system, a pair of parallel circuits, the firstcircuit comprising a relay connected in series with a resistance, thesecond circuit comprising a gaseous discharge tube connected in serieswith a resistance, a condenser having one terminal connected to thejunction between said relay and the resistance in said first circuit andhaving the other terminal coneirait, a source of electrical supplyconnected 1| in common to the other terminals of said resistances, and asource of varying control current connected to said relay and saidgaseous discharge tube.

23. In a relay control system, a pair of parallel circuits, the firstcircuit comprising a first relay, a first resistance, a secondresistance, and a second relay serially connected in the order named;said second circuit comprising a first gaseous discharge tube connectedin series with a second gaseous discharge tube; a first condenser havingone terminal connected to the junction between said relay and said firstresistance and having the other terminal connected to the junctionbetween said gaseous discharge tubes; a second condenser havingone'terminal connected to the junction between said second resistanceand said second relay and having its other terminal connected to thejunction between said gaseous discharge tubes; a third resistance havingone terminal connected to the junction between said first and secondresistances and having the other terminal connected to the junctionbetween said gaseous discharge tubes; a reactance connected in parallelwith said third resistance; said junction between said first and secondresistances being connected to one terminal of a source of electricalsupply; said first relay and said first gaseous electric discharge tubebeing connected in common to a source of varying control current; andsaid second relay and said seco d gaseous discharge tube being connectedin co mon to a second source of varying control current,

24. In a relay control system, a pair of parallel circuits, the firstcircuit comprising a relay and 4 a resistance in series, said secondcircuittcomprising a condenser connected in series with a resistance, agaseous discharge tube having one,

25. In a relay control system, a relay and a first resistance connectedin series, a condenser and a second resistance connected in a series, agaseous discharge tube having one terminal connected to the junctionbetween said relay and said first resistance and having the otherterminal connected to the junction between said condenser and saidsecond resistance, a variable resistance connected in parallel with saidcondenser and said second resistance, a common connection between saidvariable resistance, said condenser, and said relay, and a source ofelectrical supply having one terminal connected to said first resistanceand having the other terminal connected to the junction between saidsecond resistance and said variable resistance.

26.;A proportionalizing control means comprisinfiza control elementresponsive to a predeterm ed value of energy, a circuit for energizingsaid control element, and means for accumulating said energy when thesame is below said predetermined value and discharging same into saidcircuit at intervals to operate said'control element, said dischargebeing withheld until the value of said accumulated energy exceedssaidpredetermined value when the amount of energy 2'7. A prcportionalizlngcontrol means responsive to a varying voltage to exert a resultantcontrol effect proportional to the value of said voltage, comprisingcyclically operating energy accumulating and releasing means forenergizing a control relay, said means including means for varying thefrequency of said cyclical operation in accordance with the value ofsaid voltage.

28. A proportionalizing control means responsive to a varying voltage toexert a resultant control eifect proportional to the value oi saidvoltage comprising a condenser charged by said voltage, discharge meansfor said condenser in circuit responsive to the potential across thecondenser,

and a relay with-said discharge means for accomplishing said controleflects, said relay being energized by the discharge of said condenser.

29. A device for controlling the operation of a reversible electricmotor, comprising a source of electrical energy for energizing saidmotor, a pair of relays having front and back contacts for controllingthe application 01' energy from said source to said motor, one of saidrelays being normally eflective when energized to cause said motor to beoperated in one direction and the other of said relays being normallyeffective when energized to cause said motor to operate in the 'oppositedirection, an energy responsive control circuit connected with each ofsaid relays for controlling the rate of operation of said motor, asource of varying control energy for each of said control circuits .!orapplying the necessary control to said circuits, and circuit means,including the back contacts oi said relays, for preventing both of saidrelays from applying energy to said motor at the same time.

EDWARD M. SORENSEN.

